Synthesis and Performance of a Multi‐Purpose Gemini Precursor and the Derivative Alkylaryl Sulfonate Gemini Surfactants

Abstract The phenol–formaldehyde condensation reaction to synthesize a gemini precursor was renewed by using high efficient and environmentally benign resin catalysts instead of protonic acids, and the conversion, yield and selectivity of the reaction were all upgraded from the 60 % by the traditional way to over 90 % by the new way. Three alkylaryl sulfonate gemini surfactants were derived from the above gemini precursor by O‐methylation, sulfonation and neutralization, that is, sodium salt of sulfonated bis(2‐hydroxy‐5‐nonylphenyl)methane (SBHNM), sodium salt of sulfonated bis(2‐hydroxy‐5‐dodecylphenyl)methane (SBHDM) and sodium salt of sulfonated bis(2‐methoxy‐5‐nonylphenyl)methane (SBMNM). And their performances in aqueous solution were further investigated. The results show that the three gemini surfactants exhibit higher effectiveness and efficiency in surface tension reduction than a monomeric reference surfactant sodium dodecylbenzene sulfonate (SDBS). Furthermore their critical micelle concentration values are at least one order of magnitude lower than that of SDBS. It is also shown that O‐methylation of the hydroxyl group in the gemini precursor is effective at improving the surface activity of the gemini surfactants, such as efficiency in surface tension reduction, foam stability and calcium stability. It is suggested that the synthesized hydrophobic skeleton could be a multi‐purpose gemini precursor from which various gemini surfactants could be derived by further hydrophobic or hydrophilic modification.